Three-dimensional structure of frontal waves and associated salinity minimum formation along the Kuroshio Extension
Three-dimensional structure of frontal waves and associated salinity minimum formation along the Kuroshio Extension
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DOI：
10.1175/jpo3026.1
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发表时间：
2007-03-01
影响因子：
3.5
通讯作者：
Hiroe, Yutaka
中科院分区：
文献类型：
--
作者：
Kouketsu, Shinya;Yasuda, Ichiro;Hiroe, Yutaka
2002年9月进行了高分辨率水文观测，以描述黑潮延伸体沿着锋面波的详细结构。在上层和中层均观测到锋面波，分别对应于北太平洋副热带模态水和北太平洋中层水的深度。上层锋面波超前中深层锋面波约1/4波长。垂直相位滞后造成的情况下，低盐度的亲潮水在中间层叠加在上层高盐度的黑潮水，从而形成一个垂直盐度最低。沿下游方向传播的锋面波波长约200 km，相速度为0.2-0.3 m s（-1），与卫星云图上的结果一致。垂直速度场的估计准地转欧米茄方程。槽周围的下降流（从波峰到波谷）的中间深度（上层）锋面波和波峰周围的上升流（从波谷到波峰）的墨西哥湾流蜿蜒的特征相似。中高层的位相差表明锋面波是斜压不稳定波。
High-resolution hydrographic observations were conducted in September 2002 to describe the detailed structure of frontal waves along the Kuroshio Extension. Frontal waves were observed both in the upper and intermediate layers, which corresponded to the depths of North Pacific Subtropical Mode Water and North Pacific Intermediate Water, respectively. The frontal wave in the upper layer preceded the intermediate-depth frontal wave by about 1/4 wavelength. The vertical phase lag created situations in which the low-salinity Oyashio water in the intermediate layer was superimposed below the upper-layer high-salinity Kuroshio water, thus forming a vertical salinity minimum. The frontal waves with a wavelength of about 200 km and a phase speed of 0.2-0.3 m s(-1) propagating in the downstream direction were consistent with those from satellite images. Vertical velocity fields were estimated with the quasigeostrophic omega equation. Downwelling around the trough (from the crest to trough) of the intermediate-depth (upper layer) frontal wave and upwelling around the crest (from the trough to the crest) were similar to the features observed in the Gulf Stream meanders. The phase difference between the upper and intermediate layers suggested that the frontal waves were baroclinically unstable waves.